Driveshaft broke while on the Dyno....

[Beast_TR]

So I had my car on the dyno tonight to get some baseline numbers and to get everything dialed in and the first run in the driveshaft just came apart!

I just had my u-joints replace and was getting everything ready for this years track outings that I had planned and now this. I am not exactly sure why it came apart but I am wondering if a faulty install of the u-joints might be to blame because I did notice a vibration at highway speed that was not present before having the u-joints replaced. I am just hoping that the transmission is ok because at we were taking it off the dyno fluid was pouring out of the front of the trans from the dust cover.

Here is the DS

I guess the good news out of it was that before everything came undone the car was running strong and not many adjustments needed to be made.

 

[1fast6]

make sure bell housing isn't cracked.

 

[49-blues]

not very pretty! I have a chrome moly one in the for sale section with greaseless spicer 1350 universal joints and also a brand new gn pinion yoke to accept the 1350 joints using the 8.5 rear from Dennys Driveshafts-$400. shipped for everything if interested. i just bought two new nitros ready shafts cause i changed out the rears in both gns to a 9" ford and a 12 bolt moser which require different lengths. Matt 347-680-8642.

 

[Beast_TR]

May have to take ya up because initial assessment of the damage shows that I need everything from the trans output yoke to the differential yoke. The differential yoke snapped off and you can see it laying right above the driveshaft to to the left of the light.

 

[hiboom]

drive shaft

I don't know why it's so hard for the parts store to get the right u-joints I had my drive shaft fly out (broke the bolts off at the yoke ) i went to the parts store for a new set the counter guy said you mite as well bring in your old one said it could be 3 difference sizes said u-joints were the worse thing to get right so i bought all 3 sets 2 of the 3 sets would fit one set was a little small and caused a vibration the second set was to big third set fit and was fine.

 

[49-blues]

Let me know. my p0aypal is: mytquick87@yahoo.com- this driveshaft should be able to take alot of abuse, the universals are solid greaseless joints, the shaft is chromemoly- very strong hard metal, cheap insurance in the long run. its a good thing your old one didnt come through the floor boards and hurt somebody. i ve heard of jack cotton also ripping a shaft in half like that.

 

[Beast_TR]

I do not think this was caused by the u-joints being wrong because I double/triple checked to make sure I got the right ones, the part number on the was 2-3011BF which you will find all over this board as being the correct and preferred u-joint.

I think it is a problem of being a poor installation because after all the carnage the u-joints were fine. I did witness the installer using a hammer instead of a press so I think I am going to have words with that shop.

 

[Beast_TR]

Let me know. my p0aypal is: mytquick87@yahoo.com- this driveshaft should be able to take alot of abuse, the universals are solid greaseless joints, the shaft is chromemoly- very strong hard metal, cheap insurance in the long run. its a good thing your old one didnt come through the floor boards and hurt somebody. i ve heard of jack cotton also ripping a shaft in half like that.

I will have to get ahold of you and trust me I am very glad that my car had a safety loop because this could have been really bad.

 

[ttaowner]

I have a stock one for $100 plus shipping. Its still in the car !!!

 

[TR Custom Parts]

Denny's driveshaft for the win. New or the one offered by the board member. Think I would rather have the driveshaft break on the dyno instead of during a run on the track or street. Sounds like you should probably go thru the trans as see if there is any damage.

 

[TurboBuRick]

How much power broke it?

The shaft had to be damaged in the area where it broke.

It's not uncommon to use a hammer when changing u joints. Thats not to say it's ok to beat on the yoke. I have a u-joint press. I prefer to use a hammer with the adapters verses the press.

If it was dropped or put in a vice, that would definitely weaken the shaft but the damage had to be right where it broke.

 

[SGRIM]

Check the trans for sure, ask me how I know:frown:

 

[Grumpy]

Denny's driveshaft for the win. New or the one offered by the board member. Think I would rather have the driveshaft break on the dyno instead of during a run on the track or street. Sounds like you should probably go thru the trans as see if there is any damage.

X2 !!!! We have Dennys in all of our cars .

 

[Chuck Leeper]

The shaft may have had no damage prior to failure.
1. The failure is in the middle...exactly where the max stress is applied.
2. It likely had so many max rpm, [critical speed], overruns that it was fatigued to the point of failure.
3. The trans leaking at the converter likely = broken case.

Bottom line: A 20 y/o driveshaft, designed to hold 235FWHP, was used to transmit double that...

I use drive shafts from PST.. FIRST CLASS service by guys that know the business...

 

[TurboBuRick]

1. The failure is in the middle...exactly where the max stress is applied.

Good point Chuck.

 

[Otto J]

Its quite possible something broke in the trans and locked up,the force of hte dyno turning will rip the shaft in 2.
This can also happen if someone applies the brakes after a run is over and the dyno is slowing down.

 

[1fast6]

I am just hoping that the transmission is ok because at we were taking it off the dyno fluid was pouring out of the front of the trans from the dust cover.

This is what concerns me.

here is a pic of mine after driveshaft failure

put a 3" chromemoly from strange, leaving@3600 rpms with a 1.4-1.5 60ft time and no worries:biggrin:

 

[L8TRH8R]

Denny's driveshaft for the win. New or the one offered by the board member. Think I would rather have the driveshaft break on the dyno instead of during a run on the track or street. Sounds like you should probably go thru the trans as see if there is any damage.

X3 I have the nitrous ready unit with billet yokes, think they're good for 1500-2000hp, I like a little over build... Sorry about your carnage.

 

[V6RACER]

PST in Clearwater, FL

 

[Beast_TR]

Chuck, I am not doubting you and anything is possible, but I do not think that something in the trans broke, the trans is a Extreme Auto. stage 2 that is a little over a year old, never been down a track yet, and has less than 1500 not very hard miles on it.

Here is what is making think that there was an issue with the install. First the nylon lock is still in the ears of the driveshaft, I know that some will still be there but there is still a significant amount even after the breakage. Most of the ears have hammer marks on them and all are damaged in some way. The ear with the most damage you can see some of the metal was "blued". Also ever since I drove the car back from the shop there has been very noticeable vibrations from the car at highway speed. The vibrations were never present on the factory u-joints and before they were replaced the car always rode extremely smooth on the highway and around town.